Maraviroc efficacy at W24 (virological and immunological efficacy); Durability of maraviroc efficacy between W24 & W36; Cmin of maraviroc and other molecules at W4,12,24; Evaluation of the safety of maraviroc between W0 and W36. [ Time Frame: immuno-virologic evolution between week 0 and week 36 ] [ Designated as safety issue: Yes ]